Myeloma is a type of blood cancer that develops from cells in the bone marrow called plasma cells. Bone marrow is the spongy tissue found inside the inner part of some of our large bones. The bone marrow produces different types of blood cells.
What are plasma cells?
Plasma cells are part of the immune system. Normal plasma cells make proteins called antibodies. These antibodies are also called immunoglobulins.
The plasma cells make antibodies when the body responds to infections. They make different antibodies for different infections. Antibodies attack and help to kill bacteria and viruses and so protect us from infections.
There are 5 main types of antibody (immunoglobulin) – A, G, M, D and E.
How does myeloma develop?
Myeloma develops when there is a change in the DNA of the plasma cells. DNA is the instructions for the cell so it knows what to do and when. The change happens to the DNA when the bone marrow is making new plasma cells. The abnormal plasma cell then produces more abnormal cells. These are myeloma cells.
The myeloma cells produce an abnormal form of one of the types of antibody. You might hear your doctor call the antibodies abnormal proteins, paraproteins, monoclonal proteins, or a monoclonal spike. They aren't able to work normally and so can't help fight infections.
The paraprotein is often found in the blood and urine if you have myeloma. Blood and urine tests are a way of diagnosing and monitoring myeloma. As well as the whole antibody (immunoglobulin), often a small part called the free light chain (called Bence-Jones in the urine) is also made in large amounts by the myeloma plasma cells.
Myeloma doesn't form a lump or a tumour. Most of the problems it causes are because of a build up of abnormal plasma cells in the bone marrow and the paraprotein in the body. Myeloma affects areas where you have active bone marrow. This includes your arms and legs and your shoulders as well as your spine, skull, pelvis and rib cage. Myeloma affects several places in the body which is why it is sometimes called multiple myeloma.
Blood cells and myeloma
To understand why myeloma affects you the way it does, it helps to understand how blood cells are normally produced and what they do.
Usually bone marrow makes blood cells in a controlled way, when your body needs them. All blood cells start as the same type of cell, called a stem cell. As they develop (mature), they turn into one of three types of blood cell:
- white blood cells (leucocytes)
- red blood cells (erythrocytes)
- platelets (thrombocytes)
Plasma cells develop from a type of white blood cell called B lymphocytes. In myeloma, too many plasma cells are made and they are all of the same type. They crowd the bone marrow. This means that there is not enough space for making normal white cells, red cells and platelets.
What do your blood cells do?
The white cells are important for fighting infection. If you don't have enough white blood cells, you will pick up more infections, and infections might take longer to get better.
Red blood cells carry oxygen round the body. If you haven't got enough red blood cells, you have anaemia. This can make you tired and breathless.
Platelets are important for normal blood clotting. If you don't have enough platelets, you might bleed more. You might have nosebleeds, very heavy periods, or a fine rash of red spots caused by bleeding into the skin.
How common is myeloma?
Around 5,800 people are diagnosed with myeloma in the UK each year. That is 16 people every day.
Who gets it?
Myeloma is more common in men than women.
It is more common in older people. In the UK, on average each year around 45 out of 100 (around 45%) of new cases are in people aged 75 and over. It is very rare in people younger than 40.